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// mdc.h - originally written and placed in the public domain by Wei Dai
#ifndef CRYPTOPP_MDC_H
#define CRYPTOPP_MDC_H
//! \file mdc.h
//! \brief Classes for the MDC message digest
#include "seckey.h"
#include "secblock.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
//! \class MDC_Info
//! \tparam B BlockCipher derived class
//! \brief MDC_Info cipher information
template <class B>
struct MDC_Info : public FixedBlockSize<B::DIGESTSIZE>, public FixedKeyLength<B::BLOCKSIZE>
{
static std::string StaticAlgorithmName() {return std::string("MDC/")+B::StaticAlgorithmName();}
};
//! \brief MDC cipher
//! \tparam T HashTransformation derived class
//! \details MDC() is a construction by Peter Gutmann to turn an iterated hash function into a PRF
//! \sa <a href="http://www.weidai.com/scan-mirror/cs.html#MDC">MDC</a>
template <class H>
class MDC : public MDC_Info<H>
{
//! \class Enc
//! \brief MDC cipher encryption operation
class CRYPTOPP_NO_VTABLE Enc : public BlockCipherImpl<MDC_Info<H> >
{
typedef typename H::HashWordType HashWordType;
public:
void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs ¶ms)
{
CRYPTOPP_UNUSED(params);
this->AssertValidKeyLength(length);
ConditionalByteReverse(BIG_ENDIAN_ORDER, Key(), reinterpret_cast<const HashWordType*>(userKey), this->KEYLENGTH);
}
void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
ConditionalByteReverse(BIG_ENDIAN_ORDER, Buffer(), reinterpret_cast<const HashWordType*>(inBlock), this->BLOCKSIZE);
H::Transform(Buffer(), Key());
if (xorBlock)
{
ConditionalByteReverse(BIG_ENDIAN_ORDER, Buffer(), Buffer(), this->BLOCKSIZE);
xorbuf(outBlock, xorBlock, m_buffer, this->BLOCKSIZE);
}
else
{
ConditionalByteReverse(BIG_ENDIAN_ORDER, reinterpret_cast<HashWordType*>(outBlock), Buffer(), this->BLOCKSIZE);
}
}
bool IsPermutation() const {return false;}
unsigned int OptimalDataAlignment() const {return sizeof(HashWordType);}
private:
HashWordType *Key() {return reinterpret_cast<HashWordType*>(m_key.data());}
const HashWordType *Key() const {return reinterpret_cast<const HashWordType*>(m_key.data());}
HashWordType *Buffer() const {return reinterpret_cast<HashWordType*>(m_buffer.data());}
// VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup
FixedSizeSecBlock<byte, MDC_Info<H>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key;
mutable FixedSizeSecBlock<byte, MDC_Info<H>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer;
};
public:
// use BlockCipher interface
typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;
};
NAMESPACE_END
#endif
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